avdp. = avoirdupois weight, the system of weights in British and U.S.
used for goods other than gems, precious metals, and drugs.

The assay ton, used in assaying, bears the same relation to the milligram that a ton
of 2,000 pounds avoirdupois bears to the ounce troy; hence the weight in milligrams of precious metal obtained from
one assay ton of ore gives directly the number of troy ounces to the net ton.

The gross
or long ton is used commercially in the United States to only a limited extent, usually in restricted industrial
fields. These units are the same as the British “ton.”